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David Shiga writes "Astronomers have identified many objects out there that they think are black holes. But could they be portals to other universes called wormholes, instead? According to a new study by a pair of physicists, we wouldn't be able to tell the difference. They have discovered that wormholes with the right shape would look identical to black holes from the outside. But while a trip into a black hole would mean certain death, a wormhole might spit you out into a parallel universe with its own stars and planets. Exotic effects from quantum physics might produce wormholes naturally from collapsing stars, one of the physicist says, and they might even be produced in future particle accelerator experiments."

In fact, theorists say one variety of wormhole wraps back onto itself, so that it leads not to another universe, but back to its own entrance.

I'm expecting others to beat me to referencing The Black Hole [imdb.com] and Dr. Hans Reinhardt's line, "In, through, and beyond," or even Farscape [scifiquest.com] and Rigel's bored, "Wormhole. Normal space. Wormhole." So instead, and considering slashdot's current technical problems, how about something more obscure.

Wasn't this an episode of the original The Tomorrow People [tv.com], except that transit time felt like it took much longer than it really did, whereas the reality of time dilation would likely be the reverse?

A chemistry teacher of mine in high school (early 90's) of mine had a big, long lecture about the universe and built it all up from subatomic particles and ended with the vastness of space. It was his Xmas gift for his classes every year, and we loved it. Well at least those with half a brain did.

Anyway, his twist at the end resembled this article. He said that everything in the universe has gravity. Well, if everything has gravity, then the universe itself has a gravitational pull. Eventually the mass of the universe would be such that any light trying to escape it would be pulled back inside, which would make the universe appear to be black hole from anyone on the outside looking in...

Well, I'm no physicist, but it seems reasonable to me to assume that if the formation of black holes can rip through to another universe, or perhaps another part of a curved universe, then an event would take place on the other side: the formation of a matching wormhole mouth.

We have to assume that if blackholes can form in our universe, then they can form in the "other" universe. So we would be seeing the spontaneous formation of black holes occurring here that are the result of collapsing stars on the other side.

So my question is, what does this event look like from the perspective of the other side, and have we observed it happening here?

Wasn't this an episode of the original The Tomorrow People, except that transit time felt like it took much longer than it really did, whereas the reality of time dilation would likely be the reverse?

That also sounds like a Steven King short story called (IIRC) The Jaunt, where teleportation to Mars was nearly instantaneous for outside observers, but if you were awake when you traveled your consciousness perceived the transit time as nearly infinite.

Well, if everything has gravity, then the universe itself has a gravitational pull. Eventually the mass of the universe would be such that any light trying to escape it would be pulled back inside, which would make the universe appear to be black hole from anyone on the outside looking in...

It sounds like your teacher may have had the misconception that the universe is an expanding sphere, with stars and galaxies on the inside, and a void outside into which the matter expands.

That's not how Big Bang cosmology works, however. In that theory, all of space is filled with matter, and space itself expands, carrying the matter with it. There is no "edge".

Consequently, it doesn't make much sense to speak of light trying to "escape" the universe, since the universe has no boundary. That's why it's problematic to speak of the whole universe as a "black hole".

Who needs a multi-verse explaination when it suffices to explain a blackhole as vast swaths of time/space condensed to an ultra-hyperfine, darn-near-singular point? That's what I had always thought they were, anyways.

Who knows, maybe a black hole is just an area approaching infinity, shrinking all that comes to the area with it. Why not? And Hawking's Radiation naturally permeates all of the universe but remains unobservable as it's particles are so large that it would fit many solar systems in it's space, but shrinks down at a black hole to a (weakly) observable radiation. It's not as if something that large would be identifiable; it would be discounted to an observation of the basic state of the universe. Our universe is only our observable universe; all this multi-verse and worm-hole stuff isn't any more real science than my silly-sized particle, just imaginative speculation.

We have to assume that if blackholes can form in our universe, then they can form in the "other" universe.

Let's just be clear that without more details, the claim that wormholes open in some "other" universe appear quite random. The original theory of wormholes doesn't claim any other universes, just different points in the same (and only) mother universe we know.

There are two types of "other" universes currently science theorizes about: parallel universes as found in quantum theory (all possibilities of a super-state), and the universes formed by the additional dimensions suggested by the string theory (where "sliding" along the additional dimensions may create alternative universes where laws of physics change and even Pi might change as a constant).

Again, maybe just the article is written poorly, but it seems they're talking about some kind of Star Trek -style "other" universe, and we should expect lots of aliens with rubber foreheads. It's hard to take any of this seriously when all of the substance and coherence was sucked out (if it ever existed) in the process of turning it into an article.

It depends on the size of the black hole. Small ones will have sharper gravitational gradients that will result in tidal forces that could inflict serious entropy on you, but a large enough black hole could have a surface gravity less than earth and much less significant tidal forces.

The black hole is either two things to me. One it is a giant particle unknown to physics. Maybe something equivalent to the early universe particles. I heard there were alot microblackholes then. Not sure on that. The other alternative to me is a microgalaxy where space is actually condensed but still exist. Yeah,strange. Definitely good for science fiction and better than the dead nothing superparticle.

Since we can't actually travel to any suspected blackhole/wormhole-entrance, we need the dudes at CERN to whip one up, then someone can step through and hopefully wind up farther away in our own universe.

Black -> White holes was an older theory. That's NOT the theory of wormholes. A Black/White hole system is one way. Matter enters a Black Hole and exits a White Hole. Both are continually connected to one another. Additionally, your history is off, because it wasn't just a thought experiment questioning an opposite. It was an attempt to answer the question "Where does the matter entering a black hole go?" The logical answer (physics aside) would have been a white hole.

Wormhole theory is different. The theory of a wormhole is that under certain conditions, the warping of space-time can be so extreme that two massive distortions can connect to one another. Essentially, that the singularities of 2 black holes touch, and open up a tunnel through space-time, which is shorter than the trip through normal space-time. These connections can last for a single instant or longer, but they are not considered to be permanent, and are, hypothetically, rarely stable last I read.

Whether they connect to other points (black holes) within our own Universe, or within other Universes depends largely on the shape of the Universe and if multi-verse theory is even real. The shape being the major determining factor in a great deal of such very theoretical physics.

Finally, a wormhole looping back on itself would not longer join spans of space, but instead, spans of time. It would connect to it's past or future self, because doing so would involve looping, and a common theory is that the more a wormhole loops, the more it displaces itself within time.

Who knew reading a Brief History of Time so many years ago would eventually pay off?:P